Single-stranded DNA binding (SSB) proteins are a class of nonspecific DNA binding proteins that play essential roles in DNA metabolism. All organisms, including most bacteriophage and viruses, encode their own SSB proteins, all of which bind preferentially and with high affinity to single-stranded DNA (ssDNA). These proteins also generally bind ssDNA with some degree of cooperativity resulting in the tendency to form long clusters of protein when bound to ssDNA and are presumed to function, at least partly, by binding to and saturating ssDNA formed transiently during replication, recombination and repair.